fastapi uvicorn[standard] langchain-openai>=0.1.0,<0.2.0 duckduckgo-search python-dotenv pydantic langchain>=0.2.0,<0.3.0 langchain-core>=0.2.0,<0.3.0 langchain-community>=0.2.0,<0.3.0 python-multipart requests jinja2 markdown